Central vacuum systems are popular in a variety of buildings, notably family residences. A typical central vacuum system includes a vacuum pump connected to an electric motor for driving it, a plenum for generating a vacuum and duct work to another plenum for collecting debris in a vessel such as a bag and allowing exhaust air to be vented. The motor, vacuum pump and plenums are generally located in the basement or other relatively remote location within a house. A network of tubing or ducts connects the central vacuum cleaner to each of the rooms to be serviced. One or more vacuum hose connection points are located in each of the rooms to be serviced. These openings are generally covered by an air tight flap or valve to prevent the induction of air through unused openings and to maintain a vacuum within the system. A hose with a wand end is connected to one of the connection point openings when that room is to be vacuumed. The wand normally includes a handle for the user to hold and a suction head for drawing in the air and collected debris.
Difficulties with prior central vacuum systems lie with turning the central vacuum motor on and off, conveniently and reliably, determining whether the vacuum is in fact doing its job and producing enough air flow to get proper cleanability, or whether the bag or vessel for collecting debris is full. The distance from the location from the wand, or working point, to the central pump motor, generally prohibits a switch located on the vacuum motor. Because of the normal basement location of a central pump motor, climbing up and down stairs every time the user desires to use a system is inconvenient and tiring. As a result, several approaches to this problem of providing a convenient switch for operating the vacuum motor and for determining proper cleanability have been developed in the prior art.
One such attempted resolution involved mounting an electrical switch on the handle of the portable hose and routing two low voltage wires along the hose to a coupling ring on the end of the hose. When the hose is fastened to the wall opening outlet, as by use of a bayonet mount or screw mount, contact points on the coupling ring engage matching contact points on the fitting in the wall opening. The contact points on the wall opening fixture are connected to a light gauge wire pair that runs along a tubing to an electrical relay which switches the vacuum motor on and off. This system suffers from the serious disadvantages of not telling the operator how well the system is operating or giving the operator any kind of diagnostic tool that would indicate the proper system operation. The prior art only tells the operator whether the vacuum motor is operating or not operating.
An alternative approach to solving this problem is disclosed in U.S. Pat. No. 4,829,626, issued to Harkonen et al. on May 16, 1989. Harkonen discloses a method for controlling a vacuum cleaner that includes a battery operated electrical sound signal generator mounted in the handle of the wand. When the signal generator is activated, it generates and transmits a signal to the tubing, which in turn is sensed by an electrical relay which generates an electrical pulse to start the motor of the vacuum cleaner. In the Harkonen system, when an operating lever located in the handle is moved to the on position, a flap in the wand opens, allowing air to be drawn through the wand and the network of tubing to the vacuum cleaner and permitting the sound generated by the electrical signal generator to travel more easily to the electrical relay equipment located close to the vacuum cleaner motor. The sound signal is only generated momentarily in order to start the motor. Once the sound signal has been transmitted for the predetermined brief time, the sound generator is turned off. If the motor has started as intended, the motor keeps running until the flow of air through the system is blocked. It is intended that the flap and the hose near the wand be manually swung into a position across the inlet of the hose, thereby blocking the flow of air. Then a detector detects the stopping of the flow of air and in response, turns off the vacuum motor.
This proposed solution suffers also from several disadvantages. First, a chemical battery is required for operating a sound generator. The battery will necessarily run down and require replacement. More importantly, if the operator is not careful in the use of the machine, an old or run-down battery may leak corrosive chemicals into the sensitive and delicate sound generation equipment, ruining it. The battery and sound generator combination also occupy a significant volume within the handle of the wand, making the wand heavier, larger and more unwieldy.
Perhaps, the greatest difficulty with the method of Harkonen lies in the means for stopping the vacuum cleaner. In the normal course of using a vacuum cleaner, many possible events that could block the flow of air through the hose suggest Harkonen themselves. In some cases, merely pressing the vacuum head hard against a surface to be vacuumed can block the flow of air sufficiently to cause the vacuum motor to stop. This is particularly the case when the vacuum head is operated near or on non-porous materials. Further, items too large to pass conveniently through the tubing may be inadvertently sucked into the vacuum head, thereby turning it off.
Accordingly, there is a need for a remote control switching system for central vacuum systems that can reliably be turned on from the wand and that can provide instant indication of the cleanability of the vacuum cleaner system. Additionally, there is a need for a central vacuum system that includes a monitoring function to evaluate unit performance and signal when the vessel for collecting debris such as a bag is full or there is a clogged screen.